1DIG(1) BIND9 DIG(1)
2
6 dig - DNS lookup utility
7
9 dig [@server] [-b address] [-c class] [-f filename] [-k filename] [-m]
10 [-p port#] [-q name] [-t type] [-x addr] [-y [hmac:]name:key] [-4]
11 [-6] [name] [type] [class] [queryopt...]
12 dig [-h]
14 dig [global-queryopt...] [query...]
16
18 dig (domain information groper) is a flexible tool for interrogating
19 DNS name servers. It performs DNS lookups and displays the answers that
20 are returned from the name server(s) that were queried. Most DNS
21 administrators use dig to troubleshoot DNS problems because of its
22 flexibility, ease of use and clarity of output. Other lookup tools tend
23 to have less functionality than dig.
24 Although dig is normally used with command-line arguments, it also has
26 a batch mode of operation for reading lookup requests from a file. A
27 brief summary of its command-line arguments and options is printed when
28 the -h option is given. Unlike earlier versions, the BIND 9
29 implementation of dig allows multiple lookups to be issued from the
30 command line.
31 Unless it is told to query a specific name server, dig will try each of
33 the servers listed in /etc/resolv.conf. If no usable server addreses
34 are found, dig will send the query to the local host.
35 When no command line arguments or options are given, dig will perform
37 an NS query for "." (the root).
38 It is possible to set per-user defaults for dig via ${HOME}/.digrc.
40 This file is read and any options in it are applied before the command
41 line arguments.
42 The IN and CH class names overlap with the IN and CH top level domains
44 names. Either use the -t and -c options to specify the type and class,
45 use the -q the specify the domain name, or use "IN." and "CH." when
46 looking up these top level domains.
47
49 A typical invocation of dig looks like:
50 dig @server name type
52 where:
54 server
56 is the name or IP address of the name server to query. This can be
57 an IPv4 address in dotted-decimal notation or an IPv6 address in
58 colon-delimited notation. When the supplied server argument is a
59 hostname, dig resolves that name before querying that name server.
60 If no server argument is provided, dig consults /etc/resolv.conf;
62 if an address is found there, it queries the name server at that
63 address. If either of the -4 or -6 options are in use, then only
64 addresses for the corresponding transport will be tried. If no
65 usable addresses are found, dig will send the query to the local
66 host. The reply from the name server that responds is displayed.
67 name
69 is the name of the resource record that is to be looked up.
70 type
72 indicates what type of query is required — ANY, A, MX, SIG, etc.
73 type can be any valid query type. If no type argument is supplied,
74 dig will perform a lookup for an A record.
75
77 The -b option sets the source IP address of the query to address. This
78 must be a valid address on one of the host's network interfaces or
79 "0.0.0.0" or "::". An optional port may be specified by appending
80 "#<port>"
81 The default query class (IN for internet) is overridden by the -c
83 option. class is any valid class, such as HS for Hesiod records or CH
84 for Chaosnet records.
85 The -f option makes dig operate in batch mode by reading a list of
87 lookup requests to process from the file filename. The file contains a
88 number of queries, one per line. Each entry in the file should be
89 organized in the same way they would be presented as queries to dig
90 using the command-line interface.
91 The -m option enables memory usage debugging.
93 If a non-standard port number is to be queried, the -p option is used.
95 port# is the port number that dig will send its queries instead of the
96 standard DNS port number 53. This option would be used to test a name
97 server that has been configured to listen for queries on a non-standard
98 port number.
99 The -4 option forces dig to only use IPv4 query transport. The -6
101 option forces dig to only use IPv6 query transport.
102 The -t option sets the query type to type. It can be any valid query
104 type which is supported in BIND 9. The default query type is "A",
105 unless the -x option is supplied to indicate a reverse lookup. A zone
106 transfer can be requested by specifying a type of AXFR. When an
107 incremental zone transfer (IXFR) is required, type is set to ixfr=N.
108 The incremental zone transfer will contain the changes made to the zone
109 since the serial number in the zone's SOA record was N.
110 The -q option sets the query name to name. This useful do distinguish
112 the name from other arguments.
113 Reverse lookups — mapping addresses to names — are simplified by the -x
115 option. addr is an IPv4 address in dotted-decimal notation, or a
116 colon-delimited IPv6 address. When this option is used, there is no
117 need to provide the name, class and type arguments. dig automatically
118 performs a lookup for a name like 11.12.13.10.in-addr.arpa and sets the
119 query type and class to PTR and IN respectively. By default, IPv6
120 addresses are looked up using nibble format under the IP6.ARPA domain.
121 To use the older RFC1886 method using the IP6.INT domain specify the -i
122 option. Bit string labels (RFC2874) are now experimental and are not
123 attempted.
124 To sign the DNS queries sent by dig and their responses using
126 transaction signatures (TSIG), specify a TSIG key file using the -k
127 option. You can also specify the TSIG key itself on the command line
128 using the -y option; hmac is the type of the TSIG, name is the name of
129 the TSIG key and key is the actual key. If hmac is not specified, the
130 default is hmac-md5 or if MD5 was disabled hmac-sha256. The key is a
131 base-64 encoded string, typically generated by dnssec-keygen(8).
132 Caution should be taken when using the -y option on multi-user systems
133 as the key can be visible in the output from ps(1) or in the shell's
134 history file. When using TSIG authentication with dig, the name server
135 that is queried needs to know the key and algorithm that is being used.
136 In BIND, this is done by providing appropriate key and server
137 statements in named.conf.
138
140 dig provides a number of query options which affect the way in which
141 lookups are made and the results displayed. Some of these set or reset
142 flag bits in the query header, some determine which sections of the
143 answer get printed, and others determine the timeout and retry
144 strategies.
145 Each query option is identified by a keyword preceded by a plus sign
147 (+). Some keywords set or reset an option. These may be preceded by the
148 string no to negate the meaning of that keyword. Other keywords assign
149 values to options like the timeout interval. They have the form
150 +keyword=value. The query options are:
151 +[no]tcp
153 Use [do not use] TCP when querying name servers. The default
154 behavior is to use UDP unless an AXFR or IXFR query is requested,
155 in which case a TCP connection is used.
156 +[no]vc
158 Use [do not use] TCP when querying name servers. This alternate
159 syntax to +[no]tcp is provided for backwards compatibility. The
160 "vc" stands for "virtual circuit".
161 +[no]ignore
163 Ignore truncation in UDP responses instead of retrying with TCP. By
164 default, TCP retries are performed.
165 +domain=somename
167 Set the search list to contain the single domain somename, as if
168 specified in a domain directive in /etc/resolv.conf, and enable
169 search list processing as if the +search option were given.
170 +[no]search
172 Use [do not use] the search list defined by the searchlist or
173 domain directive in resolv.conf (if any). The search list is not
174 used by default.
175 +[no]showsearch
177 Perform [do not perform] a search showing intermediate results.
178 +[no]defname
180 Deprecated, treated as a synonym for +[no]search
181 +[no]aaonly
183 Sets the "aa" flag in the query.
184 +[no]aaflag
186 A synonym for +[no]aaonly.
187 +[no]adflag
189 Set [do not set] the AD (authentic data) bit in the query. This
190 requests the server to return whether all of the answer and
191 authority sections have all been validated as secure according to
192 the security policy of the server. AD=1 indicates that all records
193 have been validated as secure and the answer is not from a OPT-OUT
194 range. AD=0 indicate that some part of the answer was insecure or
195 not validated. This bit is set by default.
196 +[no]cdflag
198 Set [do not set] the CD (checking disabled) bit in the query. This
199 requests the server to not perform DNSSEC validation of responses.
200 +[no]cl
202 Display [do not display] the CLASS when printing the record.
203 +[no]ttlid
205 Display [do not display] the TTL when printing the record.
206 +[no]recurse
208 Toggle the setting of the RD (recursion desired) bit in the query.
209 This bit is set by default, which means dig normally sends
210 recursive queries. Recursion is automatically disabled when the
211 +nssearch or +trace query options are used.
212 +[no]nssearch
214 When this option is set, dig attempts to find the authoritative
215 name servers for the zone containing the name being looked up and
216 display the SOA record that each name server has for the zone.
217 +[no]trace
219 Toggle tracing of the delegation path from the root name servers
220 for the name being looked up. Tracing is disabled by default. When
221 tracing is enabled, dig makes iterative queries to resolve the name
222 being looked up. It will follow referrals from the root servers,
223 showing the answer from each server that was used to resolve the
224 lookup.
225 +dnssec is also set when +trace is set to better emulate the
227 default queries from a nameserver.
228 +[no]cmd
230 Toggles the printing of the initial comment in the output
231 identifying the version of dig and the query options that have been
232 applied. This comment is printed by default.
233 +[no]short
235 Provide a terse answer. The default is to print the answer in a
236 verbose form.
237 +[no]identify
239 Show [or do not show] the IP address and port number that supplied
240 the answer when the +short option is enabled. If short form answers
241 are requested, the default is not to show the source address and
242 port number of the server that provided the answer.
243 +[no]comments
245 Toggle the display of comment lines in the output. The default is
246 to print comments.
247 +[no]rrcomments
249 Toggle the display of per-record comments in the output (for
250 example, human-readable key information about DNSKEY records). The
251 default is not to print record comments unless multiline mode is
252 active.
253 +split=W
255 Split long hex- or base64-formatted fields in resource records into
256 chunks of W characters (where W is rounded up to the nearest
257 multiple of 4). +nosplit or +split=0 causes fields not to be split
258 at all. The default is 56 characters, or 44 characters when
259 multiline mode is active.
260 +[no]stats
262 This query option toggles the printing of statistics: when the
263 query was made, the size of the reply and so on. The default
264 behavior is to print the query statistics.
265 +[no]qr
267 Print [do not print] the query as it is sent. By default, the query
268 is not printed.
269 +[no]question
271 Print [do not print] the question section of a query when an answer
272 is returned. The default is to print the question section as a
273 comment.
274 +[no]answer
276 Display [do not display] the answer section of a reply. The default
277 is to display it.
278 +[no]authority
280 Display [do not display] the authority section of a reply. The
281 default is to display it.
282 +[no]additional
284 Display [do not display] the additional section of a reply. The
285 default is to display it.
286 +[no]all
288 Set or clear all display flags.
289 +time=T
291 Sets the timeout for a query to T seconds. The default timeout is 5
292 seconds. An attempt to set T to less than 1 will result in a query
293 timeout of 1 second being applied.
294 +tries=T
296 Sets the number of times to try UDP queries to server to T instead
297 of the default, 3. If T is less than or equal to zero, the number
298 of tries is silently rounded up to 1.
299 +retry=T
301 Sets the number of times to retry UDP queries to server to T
302 instead of the default, 2. Unlike +tries, this does not include the
303 initial query.
304 +ndots=D
306 Set the number of dots that have to appear in name to D for it to
307 be considered absolute. The default value is that defined using the
308 ndots statement in /etc/resolv.conf, or 1 if no ndots statement is
309 present. Names with fewer dots are interpreted as relative names
310 and will be searched for in the domains listed in the search or
311 domain directive in /etc/resolv.conf.
312 +bufsize=B
314 Set the UDP message buffer size advertised using EDNS0 to B bytes.
315 The maximum and minimum sizes of this buffer are 65535 and 0
316 respectively. Values outside this range are rounded up or down
317 appropriately. Values other than zero will cause a EDNS query to be
318 sent.
319 +edns=#
321 Specify the EDNS version to query with. Valid values are 0 to 255.
322 Setting the EDNS version will cause a EDNS query to be sent.
323 +noedns clears the remembered EDNS version. EDNS is set to 0 by
324 default.
325 +[no]multiline
327 Print records like the SOA records in a verbose multi-line format
328 with human-readable comments. The default is to print each record
329 on a single line, to facilitate machine parsing of the dig output.
330 +[no]onesoa
332 Print only one (starting) SOA record when performing an AXFR. The
333 default is to print both the starting and ending SOA records.
334 +[no]fail
336 Do not try the next server if you receive a SERVFAIL. The default
337 is to not try the next server which is the reverse of normal stub
338 resolver behavior.
339 +[no]besteffort
341 Attempt to display the contents of messages which are malformed.
342 The default is to not display malformed answers.
343 +[no]dnssec
345 Requests DNSSEC records be sent by setting the DNSSEC OK bit (DO)
346 in the OPT record in the additional section of the query.
347 +[no]sigchase
349 Chase DNSSEC signature chains. Requires dig be compiled with
350 -DDIG_SIGCHASE.
351 +trusted-key=####
353 Specifies a file containing trusted keys to be used with +sigchase.
354 Each DNSKEY record must be on its own line.
355 If not specified, dig will look for /etc/trusted-key.key then
357 trusted-key.key in the current directory.
358 Requires dig be compiled with -DDIG_SIGCHASE.
360 +[no]topdown
362 When chasing DNSSEC signature chains perform a top-down validation.
363 Requires dig be compiled with -DDIG_SIGCHASE.
364 +[no]nsid
366 Include an EDNS name server ID request when sending a query.
367
369 The BIND 9 implementation of dig supports specifying multiple queries
370 on the command line (in addition to supporting the -f batch file
371 option). Each of those queries can be supplied with its own set of
372 flags, options and query options.
373 In this case, each query argument represent an individual query in the
375 command-line syntax described above. Each consists of any of the
376 standard options and flags, the name to be looked up, an optional query
377 type and class and any query options that should be applied to that
378 query.
379 A global set of query options, which should be applied to all queries,
381 can also be supplied. These global query options must precede the first
382 tuple of name, class, type, options, flags, and query options supplied
383 on the command line. Any global query options (except the +[no]cmd
384 option) can be overridden by a query-specific set of query options. For
385 example:
386 dig +qr www.isc.org any -x 127.0.0.1 isc.org ns +noqr
388 shows how dig could be used from the command line to make three
390 lookups: an ANY query for www.isc.org, a reverse lookup of 127.0.0.1
391 and a query for the NS records of isc.org. A global query option of +qr
392 is applied, so that dig shows the initial query it made for each
393 lookup. The final query has a local query option of +noqr which means
394 that dig will not print the initial query when it looks up the NS
395 records for isc.org.
396
398 If dig has been built with IDN (internationalized domain name) support,
399 it can accept and display non-ASCII domain names. dig appropriately
400 converts character encoding of domain name before sending a request to
401 DNS server or displaying a reply from the server. If you'd like to turn
402 off the IDN support for some reason, define the CHARSET=ASCII
403 environment variable. The IDN support is disabled if the variable is
404 set when dig runs.
405
407 Dig return codes are:
408 0: Everything went well, including things like NXDOMAIN
410 1: Usage error
412 8: Couldn't open batch file
414 9: No reply from server
416 10: Internal error
418
420 /etc/resolv.conf
421 ${HOME}/.digrc
423
425 host(1), named(8), dnssec-keygen(8), RFC1035.
426
428 There are probably too many query options.
429
431 Copyright © 2004-2011, 2013 Internet Systems Consortium, Inc. ("ISC")
432 Copyright © 2000-2003 Internet Software Consortium.
433BIND9 Jun 30, 2000 DIG(1)